Does mercury exposure pose a risk in pregnancy?

- mercury is a metal that is present in the environment
- elemental (pure) mercury and methylmercury are 2 forms of mercury that may pose risks in pregnancy

- elemental mercury is used in thermometers, dental fillings, fluorescent light bulbs & some batteries
- dental amalgam is a silver-colored material used to fill cavities in teeth.
- it contains elemental mercury, silver and other metals
- amalgam fillings can release small amounts of mercury vapor that can be inhaled

- the FDA considers amalgam safe in adults and children over age 6
- there are few studies on the safety of amalgam in pregnant women and their babies
- some countries (Norway, Sweden and Denmark) recommend that dentists not use dental amalgam in pregnant women
- pregnant women who are concerned about the use of amalgam should discuss it with their dentist

- pregnant women who work in dental offices or in industries that use mercury to manufacture products (including electrical, chemical and mining industries) should discuss their workplace exposures with their health care providers and take all recommended precautions


- methylmercury is formed when mercury in the air is deposited in water
- the mercury comes from natural sources (such as volcanoes) and man-made sources (such as burning coal and other industrial pollution)
- fish that swim in these waters often have methylmercury in their tissues
- people become exposed to the mercury when they eat the fish
- eating fish is the main source of methylmercury exposure in humans

- trace amounts of mercury are present in many types of fish, but it is mostly found in certain large fish
- the FDA and the EPA advise pregnant women not to eat swordfish, shark, king mackerel and tilefish
- pregnant women also should limit consumption of albacore (white) tuna to 6 ounces or less a week
- all of these fish may contain enough mercury to harm an unborn baby's developing nervous system, sometimes leading to learning disabilities